A battery pack may be configured with a plurality of electronic modules that perform different functions within a battery pack. Some modules may monitor and balance battery cells while other modules may supervise operations within the battery pack and communicate battery pack conditions to a controller that is external to the battery pack. A battery pack comprised of several modules and module types has several advantages over a battery pack that is configured with a single module that provides all battery functions. Specifically, a modular system allows a manufacturer to fabricate a range of battery packs that vary in physical dimensions and functional capability while selecting battery pack components from a limited group of components.
However, producing a battery pack with multiple modules may create other challenges. In particular, if one or more modules in a battery pack recognize a condition of degradation within the battery pack, it may take longer than desired to communicate the degraded condition to other battery pack modules. In addition, if a condition of degradation is broadcast over a communication link that transfers a variety of data between battery pack modules, the condition of degradation may not be communicated if there is a disruption in the communication system.
The inventors herein have recognized the above issues and developed an approach to address them. In one approach, a method for providing notice of degradation within a battery pack, comprising: coupling a plurality of battery modules via a communication link; generating a signal in a first battery pack module, the first battery pack module at a first end of the communication link; transmitting the signal via the communication link; and opening a battery output contactor in response to a lack of the signal at a second battery pack module at a second end of the communication link.
By electrically linking battery modules in a daisy-chain configuration, it is possible to transmit a heart beat signal from one end of the daisy-chain and to receive the signal at the other end of the daisy-chain. If a module located between the ends of the daisy-chained modules experiences a condition of degradation, the module can indicate the condition of degradation by interrupting the heart beat signal. A module at the receiving end of the daisy-chain can take mitigating actions when there is an absence of the signal. For example, the module at the end of the daisy-chain can open a battery output contactor if the heart beat signal is not present for a predetermined period of time. In this way, it is possible for a plurality of modules to indicate degradation within a battery pack without each module having to broadcast the signal of degradation.
The present description may provide several advantages. In particular, the approach can reduce system complexity by providing a single daisy chain link between battery pack modules. Further, the approach can communicate a condition of degradation quickly by simply interrupting a heartbeat signal anywhere along the electrical coupling. The modules do not have to compete for priority on a communication link to indicate a condition of degradation. In addition, if there is a disruption in the electrical coupling, the system can indicate a condition of degradation since interrupting the heart beat signal indicates a condition of degradation.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.